U.S. Pat. No. 4,963,337, issued Oct. 16, 1990 to Zones, discloses a zeolite designated SSZ-33. SSZ-33 is a borosilicate material and is synthesized using a tricyclodecane quaternary ammonium ion structure directing agent (“SDA”). U.S. Pat. No. 4,910,006, issued Mar. 20, 1990 to Zones et al., discloses a zeolite designated SSZ-26. SSZ-26 does not require the presence of boron in its crystal framework, and can be an aluminosilicate. It is made using a hexamethyl[4.3.3.0]propellane-8,11-diammonium cation SDA.
SSZ-33 and SSZ-26 are members of the same series of intergrowth structures; they differ in the degree of intergrowth of the two polytype endmembers that comprise the intergrowth series. Therefore, all things being equal (i.e., heteroatom content and identity, crystallite size and morphology), the two materials should exhibit similar adsorption and catalytic behavior.
SSZ-26 can be made by first synthesizing the borosilicate SSZ-33. However, this requires a comparatively expensive SDA which requires a few steps of organic chemistry to synthesize. Once the SSZ-33 borosilicate is prepared and the SDA is removed by calcination, the framework boron must be replaced by aluminum if an aluminum-containing material is desired. To do this, the borosilicate is treated with concentrated solutions of aluminum salts. This extra step adds more cost in terms of time, chemicals, waste disposal (of the aluminum solutions), and heat treatments. Thus, a direct synthesis (i.e., one which does not require the borosilicate SSZ-33 precursor) of an aluminum-containing SSZ-26 would be preferred if a relatively inexpensive SDA could be used.
It has now been found that aluminum-containing molecular sieve SSZ-26 can be prepared directly (i.e., without having to first prepare a boron-containing molecular sieve followed by replacement of the boron with aluminum) using cis-N,N-diethyldecahydroquinolinium cation SDA.